Plant growth promoting agent

ABSTRACT

A plant growth promoting agent which contains cellulose nanofibers and which is directly or indirectly applied to, sprinkled on, or sprayed on a plant. By using cellulose nanofibers having a specific average fiber diameter and a specific average fiber length, agglomeration of the cellulose fibers is thereby suppressed. This enables efficient insecticidal effect to be realized, wherein the insecticidally active ingredient is a non-chemosynthetic material.

This Application is a National Stage of International Application No.PCT/JP2018/011666 filed Mar. 23, 2018, claiming priority based onJapanese Patent Application No. 2017-058732 filed Mar. 24, 2017.

TECHNICAL FIELD

The present invention relates to a plant growth promoting agent whichcomprises, as an active ingredient, cellulose nanofibers that have anaverage thickness of 3 to 200 nm and that are prepared by fibrillatingcellulose by means of a highly pressurized water jet and which can beused in the form of a spray.

BACKGROUND ART

Heretofore, some kind of compound is frequently used as an activeingredient of a spray agent. On the other hand, with respect toTyrophagus putrescentiae, spider mite, aphid, thrips, coccid, oribatidor the like, natural enemy mites are periodically sprinkled to effectpredation. The natural enemy mites are sprinkled on leaves once in 1.5to 2.5 months.

With a view to providing an animal ectoparasiticidal composition havingexcellent efficacy, Patent Document 1 discloses an animalectoparasiticidal composition which comprises an insecticidal ingredient(I) [wherein Q represents a C1-C3 haloalkyl group having at least onefluorine atom, or a fluorine atom; R1 and R3, which may be the same ordifferent, represent a C1-C4 chain hydrocarbon group that may besubstituted by a halogen atom, a halogen atom or a hydrogen atom; R2 andR4, which may be the same or different represent, C1-C4 chainhydrocarbon group that may be substituted by a halogen atom, —C(=G)R5, acyano group, a halogen atom or a hydrogen atom; and G represents anoxygen atom or a sulfur atom.] and an adipic acid ester; and a methodfor controlling an animal ectoparasite which characteristicallycomprises administration of an effective amount of the animalectoparasiticidal composition to animals.

With a view to providing an insect pest control agent and a method forcontrolling insect pests which have excellent attract-controlling effecton insect pests, Patent Document 2 discloses an insect pest controlagent comprising cocoa and an insecticidal active ingredient, and amethod for controlling insect pests which comprises application ofeffective amounts of cocoa and the insecticidal active ingredient onto ahabitat of insect pests.

With a view to providing an insect pest control agent and a method forcontrolling insect pests which have excellent attract-controlling effecton insect pests, Patent Document 3 discloses an insect pest controlagent comprising at least one member selected from the group consistingof milk, cheese, coffee and egg, and an insecticidal active ingredient,and a method for controlling insect pests which comprises application ofeffective amounts of the at least one member selected from the groupconsisting of milk, cheese, coffee and egg and the insecticidal activeingredient onto a habitat of insect pests.

PRIOR ART DOCUMENTS Patent Documents

Patent Document 1: Japanese Unexamined Patent Publication No.2011-153129

Patent Document 2: Japanese Unexamined Patent Publication No.2011-153131

Patent Document 3: Japanese Unexamined Patent Publication No.2011-153132

SUMMARY OF THE INVENTION Problem to be Solved by the Invention

The majority of the above conventional spray agents have such problemsthat they have high environmental burdens and possibly inflict oninfants.

In view of the above problems in the conventional techniques, it is anobject of the present invention to provide a plant growth promotingagent which can be used in the form of a spray having a lowenvironmental burden and high safety.

Means to Solve the Problem

In consideration of the above circumstances, the present inventors havemade intensive and extensive studies to find out a material havingexcellent insecticidal efficacy. As a result, they have found thatcellulose nanofibers, which have an average thickness of 3 to 200 nm andwhich are prepared by fibrillating cellulose by means of a highlypressurized water jet, have high insecticidal efficacy and also plantgrowth promoting activity and protective activity against germ, insectpest and the like. The present invention has been completed based on thefinding.

In other words, a plant growth promoting agent of the present inventioncomprises cellulose nanofibers and is directly or indirectly applied to,sprinkled on, or sprayed on a plant, and the insecticidally activeingredient thereof is non-chemo synthetic material.

The insecticidally active ingredient means an ingredient whichspecifically exhibits insecticidal activity.

The non-chemosynthetic material means a natural product prepared by achemosynthesis-free manner.

It is preferred that the cellulose nanofibers have a crystallinitydegree of 50% or more and be capable of being sprayed together with amedium.

With cellulose nanofibers having a crystallinity degree of less than50%, even if the cellulose nanofibers are deposited on spiracles ofinsect pests by spraying the cellulose nanofibers on the insect pests,action of the spiracles cannot be blocked effectively.

As the medium, for example, water may be used.

It is preferred that the cellulose nanofibers have an average thicknessof 3 to 200 nm and be prepared by fibrillating cellulose havingα-cellulose content of 60 to 99 wt. % by means of a highly pressurizedwater jet. By virtue of the α-cellulose content of 60 to 99 wt. %, thefibrillation can be advanced efficiently.

The cellulose nanofibers, which have an average thickness of 3 to 200 nmand which are prepared by fibrillating cellulose by means of a highlypressurized water jet, have strong adhesion, and thus are capable ofadhering to subjects by themselves. Accordingly, it is unnecessary touse adhesive.

It is considered that mite control by means of the spray agent as oneform of the plant growth promoting agent exerts mite control effect byblocking spiracles of mites to arrest breathing. It is furtherconsidered that cellulose nanofibers adhere to body surfaces of mites tothereby immobilize the mites. Accordingly, no additional adhesive,surfactant or the like is required, and it is effective enough forattaining mite control effect to spray only an aqueous dispersion ofcellulose nanofibers without additional adhesive, surfactant or thelike. A usual sprinkler system may be used for the spraying, enablingthe spraying to be carried out in a manpower-saving manner.

It is also effective to spray the spray agent over a domestic bedding,carpet or the like. The spray agent is safe and thus may be useddomestically at ease.

Starch also exerts an effect of blocking spiracles to arrest activity ofthe spiracles as with cellulose nanofibers. However, starch has such adrawback that if starch is sprayed on subjects, propagation of mols orthe like is likely to occur to thereby impair the plant growthenvironment. Cellulose nanofibers are not readily decomposed butdecomposed at a sluggish speed by the action of enzyme in the soil suchas cellulase. Glucose as a product resulting from the decomposition israpidly absorbed through plant roots, and thus causes no deteriorationof plant growth environment, but is rather expected to contribute growthpromotion.

The cellulose nanofibers may be prepared by causing a highly pressurizedwater jet with a pressure of about 50 to 400 MPa to collide against anaqueous slurry of 0.5 to 10 wt. % cellulose.

The cellulose nanofibers may be such that solid content in an aqueousdispersion is less than 20%. (wt. % ?)

When the cellulose nanofiber content is 0.01 wt. % or more, cellulosenanofibers exhibit acaricidal activity. When the cellulose nanofibercontent is up to 4.0 wt. %, the cellulose nanofibers can easily besprayed together with the medium by means of a usual sprayer.Accordingly, the cellulose nanofiber content is preferably 0.01 to 4.0wt. %, more preferably 0.01 to 3.0 wt. %. Further, when the cellulosenanofiber content is 0.05 to 0.15 wt. %, the cellulose nanofibersexhibit sufficient acaricidal activity.

Effect of the Invention

The plant growth promoting agent of the present invention exhibitsexcellent insecticidal activity and has a low environmental burden andhigh safety, and yet has excellent plant growing activity.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a conceptual diagram of one form of a device for preparingcellulose nanofibers as an ingredient of the plant growth promotingagent of the present invention;

FIG. 2 is a conceptual diagram showing a part of the device forpreparing cellulose nanofibers shown in FIG. 1 in an enlarged scale;

FIG. 3 is a conceptual diagram of another form of a device for preparingcellulose nanofibers as an ingredient of the plant growth promotingagent of the present invention;

FIG. 4 is a conceptual diagram of still another form of a device forpreparing cellulose nanofibers as an ingredient of the plant growthpromoting agent of the present invention;

FIG. 5 is a photograph based on which effect of the spray agent as oneform of the plant growth promoting agent of the present invention isconfirmed;

FIG. 6 is another photograph based on which effect of the spray agent asone form of the plant growth promoting agent of the present invention isconfirmed;

FIG. 7 is a photograph based on which effect of the plant growthpromoting agent of the present invention is confirmed;

FIG. 8 is graphical representation showing effect of the plant growthpromoting agent; and

FIG. 9 is another photograph based on which effect of the plant growthpromoting agent of the present invention is confirmed.

MODE FOR CARRYING OUT THE INVENTION

[(A) Cellulose Nanofiber]

In the present invention, since cellulose nanofibers having a specificaverage fiber diameter and a specific average fiber length are used as aplant growth promoting material, agglomeration of the cellulose fibersis thereby suppressed to enable efficient insecticidal effect to berealized. As the cellulose nanofibers, there may be mentioned, forexample, those derived from natural plants such as wood fibers, bamboofibers, sugarcane fibers, seed hair fibers, leaf fibers and the like;nata de coco produced by acetobacter; those produced by seaweeds, seasquirt and the lie. These cellulose nanofibers may be used alone or incombination. As the cellulose, it is preferred to use pulp havingα-cellulose content of 60 to 99 wt. %. When the cellulose has suchpurity that α-cellulose content of 60 wt. % or more, (i) fiber diameterand fiber length are regulated with ease and entanglement between fibersare thereby suppressed, and (ii) deterioration with time during storageis unlikely to occur as compared with cases where cellulose havingα-cellulose content of less than 60 wt. %, and further (iii) the effectof the present invention can be enhanced. On the other hand, ifcellulose having α-cellulose content of more than 99 wt. % is used, itis difficult to fibrillate the cellulose fiber to a nano-level.

The cellulose nanofibers in the present invention have an averagethickness of 3 to 200 nm and are prepared by fibrillating cellulose witha highly pressurized water jet.

The average thickness was measured using a field emission scanningelectron microscope JSM-7001FTTLS model produced by Japan ElectronOptics Laboratory Co., Ltd.

By virtue of the fibrillation to a 3 to 200 nm average diameter level, aplant growth promoting agent having flowability and excellentsprayability can be obtained.

If the average thickness is less than 3 nm, since dewaterability ispoor, it is undesirably difficult to increase solid content.

On the other hand, if the average thickness exceeds 200 nm, since fibershaving fiber widths of several tens μm which are not adequatelyfibrillated are included, flowability is markedly lowered andsprayability becomes poor. These are undesirable.

The fibrillation of cellulose by means of a highly pressurized water jetis carried out in such a manner that a highly pressurized water jet witha pressure of about 50 to 400 MPa is caused to collide against anaqueous slurry of 0.5 to 10 wt. % cellulose. This can be carried outusing, for example, the device for preparing cellulose nanofibers shownin FIG. 1. The device for preparing cellulose nanofibers 1 comprises asingle chamber 2, a polysaccharide slurry supply path 3 as a first fluidmedium supply path which is so disposed as to be capable of supplying acellulose slurry to the single chamber 2, and a second fluid mediumsupply path 4 which permits a non-cellulosic slurry, for example, waterto circulate therein via the single chamber 2. In the single chamber 2,an orifice injection part 5 is provided for orifice-injecting thenon-cellulosic slurry in the second fluid medium supply path 4 in adirection intersecting the direction of cellulose slurry supply from thecellulose slurry supply path 3. The cellulose slurry supply path 3permits the cellulose slurry to be circulated via the single chamber 2.

The cellulose slurry supply path 3 and the second fluid medium supplypath 4 have a mutual intersection 6 in the single chamber 2.

The cellulose slurry supply path 3 is provided with as a cellulosesupply section and comprises a tank 7 for impounding the celluloseslurry and a pump 8 which are disposed in a circulation path 9 as oneform of the cellulose slurry supply path 3. On the other hand, thesecond fluid medium supply path 4 functions as a circulation path andcomprises a tank 10, a pump 11, a heat exchanger 12, and a plunger 13,which are disposed therein.

The non-cellulosic slurry is, for example, water and comprehensivelymeans water or a fragmented cellulose slurry containing nano-fragmentedcellulose in a concentration which increases according to the degree ofprogress of the operation in such a manner that the water or fragmentedcellulose slurry is initially water contained in the tank 10 and is thencaused to pass through the mutual intersection 6 and return into thetank 10 repeatedly, as the device for preparing a cellulose nanofibers 1operates, and consequently, develops into a nano-fragmented celluloseslurry containing nano-fragmented cellulose in such a concentration.

As shown in FIG. 2, the circulation path 9 as one form of the celluloseslurry supply path 3 is so disposed as to pass through the chamber 2,and an orifice injection opening 14 of an orifice injection part 5connected to the plunger 13 in the second fluid medium supply path 4 isset to open in the chamber 2 so as to permit the non-cellulosic slurryto pass across the circulation path 9 in a direction intersecting thecirculation path 9. An outlet 15 of the chamber 2 is provided at theposition opposite to the orifice opening 14 in the chamber 2, and thecirculation path of the second fluid medium supply path 4 is connectedto the outlet 15 of the chamber 2 to constitute the second fluid mediumsupply path 4.

On the other hand, the circulation path 9 as one form of the celluloseslurry supply path 3 is formed using, for example, a vinyl hose, arubber hose or the like. On the entry side of the circulation path 9 tothe chamber 2, a one-way valve 16 is provided which opens only in thedirection toward the chamber 2. On the exit side of the circulation path9 from the chamber 2, a one-way valve 17 is provided which opens only inthe discharge direction from the chamber 2. In addition, between thechamber 2 and the one-way valve 17, the circulation path 9 is providedwith an air intake valve 18. The air intake valve 18 opens only in thedirection of air intake from the outside into the circulation path 9.

According to the above-described device for preparing cellulosenanofibers, the cellulose nanofibers are prepared as follows.

The non-cellulosic slurry is circulated through the second fluid mediumsupply path 4 via the chamber 2. Specifically, using the pump 11, thenon-cellulosic slurry in the tank 10 is caused to pass through the heatexchanger 12 and the plunger 13 and thereby circulated in the secondfluid medium supply path 4. On the other hand, the cellulose slurry iscirculated in the cellulose slurry supply path 3 via the chamber 2.Specifically, using the pump 8, the cellulose slurry in the tank 7 iscirculated in the circulation path 9 which is formed using a vinyl hose,a rubber hose or the like.

On the basis of this, the non-cellulosic slurry circulated in the secondfluid medium supply path 4 is orifice-injected against the celluloseslurry circulated in the cellulose slurry supply path 3 to pass throughthe chamber 2. Specifically, high pressure water is supplied from theplunger 13 to the orifice injection opening 14 connected to the plunger13, and the high pressure water is orifice jetted from the orificeinjection opening 14 toward the circulation path 9 under high pressureof about 50 to 400 MPa.

In consequence, the non-cellulosic slurry passes across, in a directionintersecting the circulation path 9, the inside of the circulation path9 via a through-hole defined by holes 27 a, 27 b preliminarily providedin the circulation path 9 which is formed using, for example, a vinylhose, a rubber hose or the like, while entraining the cellulose slurrycirculating in the circulation path 9. The non-cellulosic slurry whichhas passed across the circulation path 9 rushes toward the outlet 15 ofthe chamber 2 and enters the second fluid medium supply path 4. Thenon-cellulosic slurry is thereby re-circulated in the second fluidmedium supply path 4.

In the course of repetition of the above process, cellulose contained inthe cellulose slurry circulating in the cellulose slurry supply path 3to pass through the chamber 2 and the non-cellulosic slurry circulatingin the second fluid medium supply path 4 is gradually fibrillated.Accordingly, cellulose nanofibers can be obtained which has a preferablefibrillation degree according to applications and which has highuniformity.

As another approach for preparing cellulose nanofibers by fibrillatingcellulose with a highly pressurized water jet, there may be mentioned ahomogenizing treatment method in which a dispersion comprising startingmaterial fibers dispersed in a solvent is treated by means of ahomogenizer equipped with a crushing type homovalve sheet. As shown inFIG. 3, according to the homogenizing treatment method, startingmaterial fibers 101 pressure-fed in such a homogenizer under highpressure are forced to pass through a small diameter orifice 102 in theform of a narrow aperture and to collide against a wall surface of thesmall diameter orifice 102 (in particular, a wall surface of an impactring 103) and are thereby cleaved under shearing stress or cleavingaction. Thus, micro-fibrillation is effected to obtain micro-fibrilshaving substantially uniform fiber diameters.

As still another approach for preparing cellulose nanofibers byfibrillating cellulose with highly pressurized aqueous jets, an aqueouscounter collision method may be mentioned, This is such a method thatnatural cellulose fibers suspended in water are introduced into opposingtwo nozzles (FIG. 4: 108 a, 108 b) in a chamber (FIG. 4: 107) and jettedfrom these nozzles toward one point and thereby caused to collide (seeFIG. 4). With this method, jets of an aqueous suspension of naturalmicrocrystalline cellulose fibers (for example, Funacell manufactured byFunakoshi Co., Japan) are counter-collided to nano-fibrillate andthereby strip off surfaces of the fibers. This improves affinity of thefibers for water as a carrier and thereby enables the nano-fibrillatedfibers to be finally brought to a nearly dissolved state. The deviceshown in FIG. 4 is of a liquid circulation type and comprises a tank(FIG. 4: 109), a plunger (FIG. 4: 110), opposing two nozzles (FIG. 4:108 a, 108 b) and, if desired, a heat exchanger (FIG. 4: 111). In thedevice, fine particles dispersed in water are introduced into theopposing two nozzles (FIG. 4: 108 a, 108 b) and jetted from the opposingnozzles (FIG. 4: 108 a, 108 b) under high pressure to cause the fineparticles to counter collide in water. In this method, only water isused other than natural cellulose fibers, and nano-fibrillation iseffected by cleaving only interaction between the fibers, and hence nosubstantial structural change of cellulose molecules is caused.Accordingly, it is possible to obtain cellulose nanofibers with loweringof polymerization degree of cellulose associated with the cleavageminimized.

In a case where the cellulose nanofibers obtained in the above-describedmanner as such are qua spray which is one form of the plant growthpromoting agent, when the spray has such a degree of draining that solidcontent in an aqueous dispersion is less than 20%, formation ofaggregates is unlikely to occur. By virtue of this, sprayability isimproved. If the solid content is 20% or more, the cellulose nanofibersare likely to aggregate together to cause formation of aggregates. Theaggregates give rise to lowering of sprayability. The solid content ismost preferably less than 16%.

As insect pests on which the spray agent as one form of the plant growthpromoting agent of the present invention exerts insecticidal effect,there may be mentioned those listed below.

Tyrophagus putrescentiae (Schrank); Tetranychidae (spider mite);Aphididae (aphid); Thysanoptera (thrips); Coccoidea (scale insect);Oribatida (oribatid mite); Hemiptera insect pests, for example,Delphacidae (planthoppers) such as Nilaparvata lugens (brownplanthopper), Sogatella furcifera and Laodelphax striatella (small brownplanthopper), leaf hoppers such as Nephotettix cincticeps (green riceleafhopper), Nephotettix virescens, Nephotettix nigropictus, Reciliadorsalis (zig-zag rice leafhopper), Empoasca onuki (tea greenleafhopper) and Arboridia apicalis, Aphidoidea (aphids) such as Aphisgossypii (cotton aphid), Myzus persicae (green peach aphid), Aphisspiraecola Toxoptera citricidus, Ovatus malisuctus, Aulacorthum solani(potato aphid) and Brevicoryne brassicae, Hemiptera such as Blissusleucopterus (chinch bug), Cletus punctiger, Leptocorisa acta, Riptortuspedestris, Leptocorisa chinensis, Nezara viridula, Plautia stali andHalyomorpha halys (brown marmorated stink bug), Aleyrodidae (whiteflies)such as Bemicsa tabaci (tobacco whitefly), Trialeurodes vaporariorum(greenhouse whitefly), Dialeurodes citri (citrus whitefly) andAleurocanthus spiniferus (orange spiny whitefly), Ccoccocidae (scaleinsects), Tingitidae (lace bugs) and psyllids (jumping plant lice);Lepdopterous pest, for example, Pyralidae (pyralids) such as Chilosurppessalis (rice stem borer), Cnaphalocrocis medinalis, Indian mealmoth, Haritalodes derogate, yellow stem borer, Chilo polycrysus,Nymphula depunctalis, Conogethes punctiferalis, Euzophera batangensis,Ostrinia scapulalis, Evergestis forficalis, Southwestern Corn Borer andEuropean Corn Borer; Noctudiae, such as Spodoptera litula (tobaccocutworm), Mythimna separate, Mamestra brassicae (cabbage army worm),Sesamia inference, Spodoptera mauritia, Naranga aenescence (green ricecaterpillar), Agrotis ipsilon (black cutworm), Spodoptera exigua,Cosmophila flava, Helicoverpa armigera (tobacco budworm), Garellaruficirra, Telorta divergens, Eudocima tyrannus, Oraesia excavate,Agrotis segetum (turnip moth), Agrotis ipsilon (black cutworm),Autographa nigrisigna, Thysanoplusia intermixta (chrysanthemum goldenplusia), Ctenoplusia agnata, Aedia leucomelas and Cotton Leafworm;Pieridae such as Artogeia rapae crucivola (white cabbage butterfly,cabbageworm); Tortricidae (budworm) such as Adoxophyes honmai (smallertea tortrix), Homona magnanima (tea tortrix), Archips breviplicana,Adoxophyes orana fasciata, Archips fuscocupreanus, Adoxophyes orana,Archips xylosteana, Cydia kurokoi, Sparganosis pillariana, Choristoneuralongicellana, Archips breviplicana, Epiblema leucantha and FruittreeLeafroller; Olethreutinae; Hesperiidae (skippers) such as Parnaraguttata (rice leaf-tier); Carposinidae; Lyonetiidae (leafminer moths);Phyllocnistis citrella; Gracillariidae; Gelechiidae; Oecophridae; Artaxasubflava (tussock moth); Psychidae; Stathmopodidae; Gastropachaorientalis; Stauropus fagi; Zygaenidae (burnet moth); Sphingidae (hawkmoths); Geometridae; Sesiidae (clearwing moth); Peterophoridae (plumemoth); Monema flavescens; Heliothis spp. such as Plutella xyrostella(diamondback moths), Tinea translucens (clothes moths) and Tineolabisselliella (webbing clothes moths); Diptera pests (two-winged flies),for example, Culex (house mosquito) such as Culex pipiens (common housemosquito) and Culex tritaeniorhynchus, Aedes (striped mosquitos) such asAedes aegypti (yellow fever mosquito) and Aedes albopictus (tigermosquito), Anophelinae such as Anopheles sinensis, Chironomidae (midge),Muscidae such as Musca domestica (housefly) and Muscina stabulans,Calliphoridae (blowfly), Sarcophagidae (flesh fly), Anthomyiidae such asFannia canicularis, Delia platura (seed-corn fly) and Delia antiqua(onion fly), Cecidomyiidae (gall midge), Tephritidae (fruit fly),Ephydridae, Drosophilidae (vinegar fly), Psychodidae (moth fly),Tabanidae (horsefly), Simuliidae (black fly) and Stomoxys calcitrans(stable fly); Coleoptera, for example, Curculionidae, Anthonomusgrandis, Lissorhoptrus oryzophilus (rice water weevil), Echinocnemussquamous (rice plant weevil), Japanese weevil, Sitophilus zeamais (maizeweevil) and Callosobruchus (adzuki bean weevil), Chrysomelidae (leafbeetle) such as Oulemia oryzae (rice leaf beetle), Banded CucumberBeetle, Western Corn Rootworm, Northern Corn Rootworm, Southern CornRootworm and Paddy Hispid, Tenebrionidae (darkling beetle) such asTenebrio molitor and Tibolium castaneum (flour beetle), Cerambycidae(long-horned beetle) such as Anoplophora malaciaca (white-spottedlongicorn beetle) and Xylotrechus phyrrhoderus, Scarabaeidae such asAnomara cuprea, Popillia japonica and Anomara rufocupra (soybeanbeetle), Nitidulidae, Chrysomelidae (leaf beetle) such as Phyllotretastriolata, Phaedon brassicae and Aulacophora femoralis (cucurbit leafbeetle), Scolytidae (bark beetle), Coccinellidae (ladybird beetle),Lyctidae, Bostrichidae, Attelabidae, Elateridae (click beetle),Coccinellidae (ladybird) such as Henosepilachna vigintioctopunctata, andAnobiidae (deathwatch); Dictyoptera such as Blattellidae (Germancockroach), Periplaneta fuligionosa (smokybrown cockroach), Periplanetaamericana (American cockroach), Periplaneta brunnea (brown cockroach)and Blatta orientalis; Thysanoptera such as Thrips palmi (melon thrips),Scirtothrips dorsalis and Thrips hawaiiensis; Hymenoptera, for example,Formicidae, and Tenthredinidae (sawfly) such as Athalia rosae;Orthoptera such as Gryllotalpa africana (mole cricket) and Acrididae(grasshopper); Siphonaptera such as Pulex irritants; Anoplura (louse)such as Pediculus humans (body louse) and Pthirus pubis; and Isopterasuch as Reticulitermes speratus and Formosan subterranean termite.

Of these, as insect pests on which the spray agent as one form of theplant growth promoting agent of the present invention exertsparticularly excellent effect, there may be mentioned soil insect pests(insects or the like which inhabit in the soil and damage toagricultural crops), for example, Diabrotica of Chrysomediae, e.g., cornrootworms such as Diabrotica virgifera virgifera LeConte (western cornrootworm), Diabrotica barberi Smith and Lawrence (northern cornrootworm), and Diabrotica undecimpunctsata howardi (southern cornrootworm), Aulacophora such as Auracophora femoralis Motschulsky(cucurbit leaf beetle), Phyllotreta such as Phyllotreta striolata(Fabricius) (striped flea beetle), (Scarabaeidae) Maladera such asMaladera castanea, Anomala such as Anomala cuprea Hope (cupreouschafer), Anomala rufocuprea Motshulsky (soybeen beetle) and Anomaladaimiana, Harold, and Papillia such as Papillia japonica Newman(Japanese beetle).

When a spray agent as one form of the plant growth promoting agent ofthe present invention is used qua active ingredient, it is preferredthat the L spray agent as one form of the plant growth promoting agentof the present invention be contained qua active ingredient in a mediumsuch as water in an amount of 0.01% to 4.0%, preferably 0.05% to 0.15%in terms of weight ratio. The spray may be mixed with a variety of gasand thereby formulated into an aerosol or the like. As a gaseouscarrier, i.e., propellant, there may be mentioned chlorofluorocarbon(CFC) gas, butane, carbon dioxide or the like.

EXAMPLES

Hereinbelow, the present invention will be described more specificallywith reference to the following Examples. However, the present inventionis by no means limited to the Examples.

The active ingredient used in Examples is cellulose nanofibers: tradename (Nanoforest-S®) [manufactured by Chuetsu Pulp & Paper Co., Ltd;average thickness: 36.5 nm; α-cellulose content: 85 wt. %].

Test Example 1

An aqueous dilution of cellulose nanofibers was sprinkled over a sectionhaving an area of 200 tsubo (about 661 m²), which is one block in agreen house controlled at a temperature of 14° C. or higher. In thismanner, by carrying out the verification test only in the specificcontrol area in the green house, escape of mites, insects or the liketales place. This enables pest repelling effect to be confirmed.

Agricultural chemicals exhibit insecticidal effects by the action ofactive ingredients, whereas cellulose nanofibers cover fruits to therebyprotect them. Agricultural chemicals and cellulose nanofibers arefundamentally different in effect and mechanism. As shown in FIG. 5,two-spotted spider mites on which 0.1% cellulose nanofiber aqueoussuspension was directly sprinkled were confirmed to be dead. This isprobably because cellulose nanofibers block spiracles of the mites aswith starch or the like to suppress breathing of the mites, therebyenabling control of the mites to be realized. Although agriculturalchemicals are diluted by about 1,000 times for use, the cellulosenanofibers could be used in such a concentration that a 1% productthereof was diluted by about ten times.

Test Example 2

Effect of cellulose nanofibers on two-spotted spider mites wasconfirmed. On adults of two-spotted spider mite as subjects, cellulosenanofibers were directly sprinkled to confirm the effect. As shown inTable 1, with respect to 0.05% cellulose nanofiber aqueous dispersion,number of fatalities was 2 relative to number of the subjects of 3. Withrespect to 0.1% cellulose nanofiber aqueous dispersion, such effectcomparable to that of already-existing agricultural chemicals:Akaritouch® manufactured by Toagosei Co., Ltd. was attained that numberof fatalities was 8 relative to number of subjects of 8.

TABLE 1 material sprayed on two-spotted number of spider mites (directlysprinkled) subjects (fatality) Water 5 (0) cellulose nanofibers 0.1% 8(8) cellulose nanofibers 0.05% 3 (2) cellulose nanofibers 0.02% 6 (0)Akarituoch ® manufactured by 7 (7) Toagosei Co., Ltd.

Teat Example 3

1% cellulose nanofiber dispersion was diluted 100 times with water, thiswas sprayed on mandarin orange trees every about 50 days. As a result,no occurrence of black spots caused by rust mites was observed, whichcause rust mite disease that is one of diseases of mandarin orange.

As Comparative Example, Sanmaito water-dispersible powder which isalready-existing agricultural chemicals was diluted 2,000 times, andthis was sprinkled on mandarin orange trees. No appearance of rust miteswas observed also in this case. Further, dani-getter flowable which isalready-existing agricultural chemicals was diluted 2,000 times, andthis was sprinkled on mandarin orange trees. No appearance of rust miteswas observed also in this case.

As shown in FIG. 6, it is observed that when a dispersion of cellulosenanofibers was sprinkled on the mandarin orange trees, leaves collectedfrom the mandarin orange trees on which the dispersion was sprinkledwere larger as compared with those collected from mandarin orange treeson which no dispersion was sprinkled. From this, it is believed thatphotosynthesis took place more actively and efficiently to thereby yieldtasty mandarin oranges in the mandarin orange trees on which thedispersion was sprinkled as compared with the mandarin orange trees onwhich no dispersion was sprinkled.

Further, when the plant growth promoting agent of the present inventionis sprinkled on a plant, the plant growth promoting agent of the presentinvention constitutes a protective coating on the surface of the plantto inhibit invasion of bacteria, insect pests or the like.

In addition, the plant growth promoting agent of the present inventionsprinkled and thereby deposited on the surface of the plant penetratesinto soil, for example, by rainfall and decomposed into sugar, aceticacid or the like by degradative enzyme such as cellulase present in thesoil, thereby improving microbial distribution in the soil towarddesirable environmental order for plant growth.

Test Example 4

FIGS. 7 to 9 show results of use of the plant growth promoting agent ofthe present invention in soil irrigation in a growth environment of ivy.As shown in FIGS. 7 and 9, it is observed that growth of rootlets wasbetter in the case where irrigation was carried out using the plantgrowth promoting agent of the present invention as compared with a casewhere irrigation was carried out using water. Further, as shown in FIG.8, it is seen that the case where irrigation was carried out using theplant growth promoting agent was superior in any of development, yieldamount and dry matter weight of ivy as compared with the case whereirrigation was carried out using only water. Therefore, the plant growthpromoting agent of the present invention was confirmed to be effectivefor promotion of root spread of ivy.

Test Example 5

In the next place, sprayability of the plant growth promoting agent ofthe present invention was evaluated, and the results are shown in Table2.

Spray test of the plant growth promoting agent of the present inventionwas carried out at room temperature using a commercially available spraycontainer, and Table 2 shows the results of the spray test. Theevaluation was made in accordance with the following criteria.

◯: Mist spread out uniformly.

Δ: Mist spread out non-uniformly at times, or extent of the spreaddiminished.

x: Not sprayable

As shown in Table 2, when cellulose nanofiber content in the medium inthe plant growth promoting agent of the present invention was up to 3.0wt. %, mist spread out uniformly, whereas when the cellulose nanofibercontent was 4.0 wt. %, mist spread out non-uniformly at times or extentof the spread diminished. Further, when the cellulose nanofiber contentwas 5.0 wt. %, the dispersion could not be sprayed. From the results,when the plant growth promoting agent of the present invention is usedin the form of a spray, cellulose nanofiber content in a medium shouldbe less than 5.0 wt. % and is preferably 4.0 wt. % or less, morepreferably 3.0 wt. % or less.

TABLE 2 CNF cont. in medium (wt. %) 0.5 1.0 2.0 3.0 4.0 5.0 Evaluation ∘∘ ∘ ∘ Δ x

In the following, test results will be described which demonstrate thatthe plant growth promoting agent of the present invention isenvironment-friendly and highly safe.

Using cellulose nanofibers which have a structural formula representedby [Chem 1] below, and a molecular formula represented by [Chem 2] belowand a molecular weight of about 85,000 and which are manufactured byChuetsu Pulp & Paper Co., Ltd. (hereinafter referred to as“Nanoforest-S®”), presence or absence of micronucleus induction in 7week-old Crl: CD1(ICR) male mice was examined. Administration wascarried out by two times continuous forced oral administration at aninterval of 24 hours.

In a preliminary test where a dose was set in a range of 90.0 to 360mg/kg/day, the maximum tolerated dose of the test substance on the basisof death of the animals was estimated to be 360 mg/kg/day in both maleand female subjects. Accordingly, the implementable maximum dose of 360mg/kg/day was determined to be the highest dose of the test substance,and doses of 180 mg/kg/day and 90 mg/kg/day resulting from two-foldserial dilution (common ratio: 2) of the highest dose were set. Thethree doses were consequently set in total, and micronucleus test wascarried out. Since it was deemed that there is no substantial genderdifference in toxicity, only male animals were employed. As controlgroups, a negative control group and a positive control group wereprovided. To the negative control group, a medium (distilled water) wasadministered in a dose of 20 ml/kg by two times continuous forced oraladministration. To the positive control group, mitomycin C wasadministered in a dose of 2 mg/kg/day by single-dose intraperitonealadministration.

In the micronucleus test, even 24 hours after the second administrationas a specimen preparation time, no death of animals was observed withrespect to any of the doses of the test substance group up to thehighest dose of 360 mg/kg/day. Accordingly, the established three dosesware selected as doses for specimen observation with respect to the testsubstance group, and frequency of appearance of micronucleatedpolychromatic erythrocyte in bone marrow cells (MNPCE/PCE) was examined.

In any of the doses of the test substance group subjected to thespecimen observation, MNPCE/PCEs were within the range of the backgrounddata of the negative control. Based on this, it was deemed that nosubstantial increase was caused in appearance of micronucleatedpolychromatic erythrocyte by the administration of the test substance.

It was determined from the above results that Nanoforest-S® induced nomicronuclei under the conditions of this test.

Using EpiOcular™ EIT (OCL-200), presence or absence of eye irritancy ofNanoforest-S® was examined.

In the eye irritation test, cell viability with respect to Nanoforest-S®was 99.8% which was in excess of 60% as the criterion.

Therefore, Nanoforest-S® was determined to be “non-irritant” under theconditions of this test (not classified in UN GHS).

Using LabCyte EPI-MODEL 24, presence or absence of skin irritation withNanoforest-S® was examined.

In the skin irritancy test, cell viability with respect to Nanoforest-S®was 104.5% which was in excess of 50% as the criterion.

Therefore, Nanoforest-S® was determined to be “non-irritant” under theconditions of this test (not classified in UN GHS (including category3)).

Using lung fibroblasts of Chinese hamster (CHL/IU cells), presence ofabsence of clastogenicity of Nanoforest-S® was examined.

According to the results of the chromosomal aberration test, appearancefrequencies of cells having structural chromosome aberration and cellshaving numerical chromosome aberration were within the range of thebackground data of the negative control with respect to all the examineddoses of the test substance in any of short-time processing method inthe absence of S9 mix, short-time processing method in the presence ofS9 mix, and 24 hour continuous processing method. Accordingly, bothstructural chromosome aberration and numerical chromosome aberrationwere deemed to be negative.

It was determined from the above results that Nanoforest-S® induced nochromosome aberrations under the conditions of this test.

NOTE ON REFERENCE NUMBERS

-   -   2 . . . chamber    -   4 . . . fluid medium supply path    -   8, 11 . . . pump    -   7, 10 . . . tank    -   12 . . . heat exchanger    -   13 . . . plunger    -   9 . . . circulation path    -   3 . . . cellulose slurry supply path    -   14 . . . orifice-injection opening    -   27 a, 27 b . . . through hole

The invention claimed is:
 1. A plant growth promoting spray agent whichcomprises insecticidally active cellulose nanofibers; wherein theinsecticidally active cellulose nanofibers have a crystallinity degreeof 50% or more, wherein the insecticidally active cellulose nanofibershave an average thickness of 3 to 200 nm, and wherein the insecticidallyactive cellulose nanofibers are obtained from cellulose havingα-cellulose content of 60 to 99 wt %.
 2. The plant growth promotingspray agent as claimed in claim 1, wherein the insecticidally activecellulose nanofibers are capable of being sprayed together with a mediumpresent in the plant growth promoting spray agent.
 3. The plant growthpromoting spray agent as claimed in claim 1, wherein the insecticidallyactive cellulose nanofibers are prepared by fibrillating cellulosehaving α-cellulose content of 60 to 99 wt. % in the cellulose by meansof a highly pressurized water jet.
 4. A plant growth promoting sprayagent comprising an aqueous dispersion of insecticidally activecellulose nonofibers in an amount of 0.01 to 4.0 wt. %; wherein theinsecticidally active cellulose nanofibers have a crystallinity degreeof 50% or more and an average thickness of 3 to 200 nm, wherein theinsecticidally active cellulose nanofibers are prepared by fibrillatingcellulose having α-cellulose content of 60 to 99 wt. % in the celluloseby means of a highly pressurized water jet, and wherein theinsecticidally active cellulose nanofibers are capable of being sprayedtogether with an aqueous medium of the spray agent.
 5. The plant growthpromoting spray agent as claimed in claim 4, which consists essentiallyof a dispersion of the insecticidally active cellulose fibers in water.6. A plant growth promoting spray agent comprising an aqueous dispersionof cellulose nanofibers in an amount of 0.01 to 4.0 wt. %; wherein thecellulose nanofibers have a crystallinity degree of 50% or more and anaverage thickness of 3 to 200 nm, wherein the cellulose nanofibers areprepared by fibrillating cellulose having α-cellulose content of 60 to99 wt. % in the cellulose by means of a highly pressurized water jet,and wherein the cellulose nanofibers are capable of being sprayedtogether with an aqueous medium of the spray agent.
 7. The plant growthpromoting spray agent as claimed in claim 6, which consists essentiallyof a dispersion of the cellulose nanofibers in water.